1、 ························装·······················订························密························封························线························· 大学:_____________ 年级:____________ 专业:____________________ 姓名:_______________ 学号:________________ ························阅·······
2、················卷························密························封························线························· 《概率统计》试卷(C) (110分钟) 题 号 一 二 三 四 五 六 总 分 得 分 阅卷人 得 分 阅卷人 一、
3、求下列问题的概率(第一、二小题各8分,第三、 四小题各12分,共40分) 1、从由数字1,2,3,4,5组成的所有没有重复数字的5位数中随机抽取一个,求这个数大于23000且小于43000的概率. 2、从装有4个红球,3个白球的袋中随机取出3个球,求其中恰有2个红球1个白球的概率. 3、一批产品的次品率是0.1%,(1)用二项分布计算1000件这种产品种次品数大于2的概率;(2)用普阿松定理计算1000件这种产品种次品数大于2的概率. 4、某地区暴雨天气的概率为0.4%,某气象台对该地区暴雨天气
4、的准确预报率为95%,但也会有2.5%的非暴雨天气被误报为暴雨; (1)(6分)随机抽取该气象台对该地区的一次预报,求预报为暴雨天气的概率; (2)(6分)该气象台对该地区的一次预报为暴雨,求该地区真正为暴雨天气的概率. 得 分 阅卷人 二、(满分12分) ························装·······················订························密························封························线························
5、· 大学:_____________ 年级:____________ 专业:____________________ 姓名:_______________ 学号:________________ ························阅·······················卷························密························封························线························· 抛掷三次质地均匀的硬币,以X表示出现正面的次数,以Y表示正面出
6、现次数与反面出现次数之差的绝对值. (1)(6分) 求(X,Y)的联合分布; (2)(6分) 求X与Y的边际分布列;讨论X与Y的独立性。 得 分 阅卷人 三、(满分14分) 设随机变量X的概率密度函数为 (1)(4分) 求常数; (2)(6分) 求X的分布函数; (3)(4分) 计算 得 分 阅卷人 四、(满分12分) ························装·······················订························密·················
7、·······封························线························· 大学:_____________ 年级:____________ 专业:____________________ 姓名:_______________ 学号:________________ ························阅·······················卷························密························封························线···
8、······················ 设随机变量X的概率密度为 求:(1)(6分) 求; (2)(6分) 求的概率密度 得 分 阅卷人 五、(满分12分) 设二维随机变量的概率密度为 求(1)(6分); (2)(6分),的边缘密度函数. 得 分 阅卷人 六、(满分10分) ························装·······················订························密························封········
9、················线························· 大学:_____________ 年级:____________ 专业:____________________ 姓名:_______________ 学号:________________ ························阅·······················卷························密························封························线························· 若为常数,随机变量的密度函数 证明:对任意,都有. (共8页) 第7页 (共8页) 第8页






